Removable swirler assembly for a combustion liner

ABSTRACT

A novel and improved swirler assembly for use in a combustion liner of a gas turbine engine is disclosed. The swirler assembly is removable and sized to provide an improved assembly, repairability, and fit-up in the combustion liner. The swirler assembly includes a premix tube, premix swirler and a plurality of axially spaced mounting blocks for receiving removable fasteners for securing the swirler assembly to the combustor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 61/815,835, filed on Apr. 25, 2013. This application is relatedby subject matter to commonly-assigned U.S. Non-Provisional patentapplications entitled PREMIXER ASSEMBLY FOR GAS TURBINE COMBUSTOR(Attorney Docket No. PSM-317/PSSF.199281) and SWIRLER ASSEMBLY ANDSTIFFENING MECHANISM FOR PREMIXER ASSEMBLY OF A GAS TURBINE COMBUSTOR(Attorney Docket No. PSM-318/PSSF.199282) and assigned to the sameassignee as the present application.

TECHNICAL FIELD

The present invention generally relates to a gas turbine combustor. Morespecifically, the present invention is directed towards a removableswirler portion of combustion liner having features designed to enhancecombustor performance and increase component life through improvedassembly and disassembly techniques and improved cooling configurations.

BACKGROUND OF THE INVENTION

In a typical gas turbine engine, a compressor having alternating stagesof rotating and stationary airfoils is coupled to a turbine through anaxial shaft, with the turbine also having alternating stages of rotatingand stationary airfoils. The compressor stages decrease in size in orderto compress the air passing therethrough. The compressed air is thensupplied to one or more combustors, which mixes the air with fuel. Anignition source proximate the one or more combustors ignite the mixture,forming hot combustion gases. The expansion of the hot combustion gasesdrives the stages of a turbine, which is coupled to the compressorthrough an axial shaft. The exhaust gases can then be used as a sourceof propulsion, to generate steam through a heat recovery steamgenerator, or in powerplant operations to turn a shaft coupled to agenerator for producing electricity.

The combustion system of a gas turbine engine can take on a variety ofconfigurations. A combustion system for a gas turbine engine cancomprise a single combustion chamber, a plurality of individualcombustion chambers spaced about the axis of the engine, a plenum-typecombustion system, or a variety of other combustion systems. Dependingon the engine geometry, performance requirements, and physical operatinglocation, the exact combustor arrangement will vary.

One such combustion system comprises a casing secured to the frame ofthe engine, a combustion liner secured within at least a part of thecasing, and one or more fuel nozzles positioned within or adjacent tothe combustion liner for injecting a fuel (gas, liquid, or both) intothe combustion chamber. The combustion system is in fluid communicationwith the engine. More specifically, the casing and liner arrangementprovides a way for air from the compressor to enter the combustionsystem, where it mixes with fuel from the one or more fuel nozzles. Thefuel-air mixture is ignited by an ignition source, such as a sparkigniter. Hot combustion gases travel through the combustion liner andoften through one or more transition pieces and into the turbine. Thetransition piece is essentially a duct having a geometry that changesfrom the shape of the combustor to the inlet of the turbine.

The combustion liner is at the center of combustor operations. Thecombustion liner geometry is dictated by a variety of factors includingthe operating parameters of the engine, performance requirements, andavailable geometry. While combustion liner geometries can vary, thecombustion liner typically includes at least a portion for receivingfuel nozzles, for mixing fuel and air together and for containing thereaction when the fuel and air mixture is ignited.

Combustion liners of the prior art have met certain performancerequirements, but have also exhibited various shortcomings. For example,prior combustion liners have been primarily or exclusively weldedassemblies, thereby making it difficult for operators or repairfacilities to access all of the features of the combustion liner to berepaired. Furthermore, prior combustor designs of similar structure werecapable of operating approximately 8,000 hours prior to refurbishment orreplacement. In an effort to improve gas turbine engine efficiency,there is a strong desire in the operator community to be able to extendthe timeframe between repairs, so as to reduce engine downtime andrepair/overhaul costs.

SUMMARY

In accordance with the present invention, there is provided a novel andimproved swirler assembly for use in a combustion liner of a gas turbineengine. The swirler assembly is removable and sized to provide animproved assembly, repairability, and fit-up in the combustion liner. Aplurality of main swirler assemblies are located in a combustion linerabout a central axis and sized to receive a plurality of fuel nozzles.

In accordance with an embodiment of the present invention, there isprovided a swirler assembly for a gas turbine combustor comprising apremix tube, a premix swirler positioned within the premix tube, a firstmounting block positioned along an outer wall of the premix tubeproximate an inlet end and having a plurality of first holes, and asecond mounting block also positioned along the outer wall of the premixtube, the second mounting block spaced a distance from the firstmounting block and having one or more second holes perpendicular to theplurality of first holes.

In accordance with another embodiment of the present invention, there isprovided a multi-point, multi-directional fastening assembly for use ina gas turbine combustor comprising a first mounting block secured to abody with the first mounting block having a forward face, an opposingaft face, generally parallel side faces, an arc-shaped outer face and aplurality of holes located in the arc-shaped outer face. The fasteningassembly also comprises a second mounting block secured to the body andhaving one or more holes, where the plurality of holes in the firstmounting block are oriented generally perpendicular to the one or moreholes in the second mounting block.

In accordance with yet another embodiment of the present invention thereis provided a removable swirler assembly in a combustor comprising agenerally cylindrical body, a center core and a plurality of vanesextending between the center core and the generally cylindrical body.The removable swirler assembly also comprises a first mounting blocksecured to the generally cylindrical body where the first mounting blockhaving a forward face, an opposing aft face, generally parallel sidefaces, an arc-shaped outer face and a plurality of holes located in thearc-shaped outer face. The removable swirler assembly also comprises asecond mounting block secured to the body and having one or more holes,where the removable swirler is fastened to the combustor at both thefirst and second mounting blocks through a plurality of removablefasteners.

Additional advantages and features of the present invention will be setforth in part in a description which follows, and in part will becomeapparent to those skilled in the art upon examination of the following,or may be learned from practice of the invention. The instant inventionwill now be described with particular reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The present invention is described in detail below with reference to theattached drawing figures, wherein:

FIG. 1 is a partial cross section view of a gas turbine engine of theprior art in which a combustion system in accordance with an embodimentof the present invention is capable of being used;

FIG. 2 is a cross section view of a gas turbine combustor of the priorart capable of operating within the gas turbine engine of FIG. 1;

FIG. 3 is a perspective view of a combustion liner incorporating anembodiment of the present invention;

FIG. 4 is a cross section view of a combustion liner incorporating anembodiment in accordance with an embodiment of the present invention;

FIG. 5 is an alternate view of the cross section of FIG. 4,incorporating an embodiment of the present invention;

FIG. 6 is a cross section view of a combustion liner taken through theswirler assembly in accordance with an embodiment of the presentinvention;

FIG. 7 is an alternate view of the cross section of FIG. 6, inaccordance with an embodiment of the present invention;

FIG. 8 is a perspective view of a swirler assembly portion of thecombustion liner of FIG. 3 in accordance with an embodiment of thepresent invention;

FIG. 9 is a detailed cross section view taken through an inlet portionof the combustion liner of FIG. 3 including a cross section of theswirler assembly in accordance with an embodiment of the presentinvention; and,

FIG. 10 is a partial cross section view of the swirler assembly of thecombustion liner in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION

The subject matter of the present invention is described withspecificity herein to meet statutory requirements. However, thedescription itself is not intended to limit the scope of this patent.Rather, the inventors have contemplated that the claimed subject mattermight also be embodied in other ways, to include different components,combinations of components, steps, or combinations of steps similar tothe ones described in this document, in conjunction with other presentor future technologies.

Referring initially to FIG. 1, a gas turbine engine 100 of the prior artis depicted in partial cross section. The gas turbine engine 100generally comprises an outer casing 102, enveloping the main portions ofthe engine. A shaft 104 extends axially along an engine axis A-A and iscoupled to a compressor 106 and a turbine 108. The compressor 106receives air through inlet region 110 and directs the air throughalternating rows of rotating and stationary airfoils of decreasing sizein order to compress the air as it passes therethrough, therebyincreasing the temperature and pressure of the air. The compressed airis then directed through one or more combustion systems 112 where fueland air are mixed together and ignited to form hot combustion gases. Thehot combustion gases are then directed into the turbine 108 and throughalternating rows of rotating and stationary airfoils of increasing size,so as to expand the fluid and convert the energy of the combustion gasesinto mechanical work to drive the shaft 104. The shaft 104 may also becoupled to a shaft of an electrical generator for purposes of generatingelectricity (not shown).

FIG. 2 discloses a cross section of a combustor 200 of a gas turbineengine of the prior art. As such, this typical gas turbine combustor 200comprises a casing 202, a cover 204, one or more fuel injectors 206, anda combustion liner 208. A transition piece 210 connects the combustionliner 208 to an inlet of the turbine 212.

The present invention is shown in detail in FIGS. 3-10 and discloses anew and improved removable swirler assembly for use in a combustor of agas turbine engine. Referring initially to FIGS. 3-7, a combustion liner300 having a removable swirler assembly 332 is disclosed. The combustionliner 300 comprises a generally cylindrical liner body 302 having aninlet end 304, an outlet end 306, or discharge end, and an axis B-Bextending through the combustor. The combustion liner 300 is generallycylindrical in cross section, but it is understood that the combustionliner 300 can vary in shape, have tapered sections, or sections ofvarying diameter. The combustion liner 300 is generally fabricated fromrolled sheet metal that is welded along an axial seam and can be formedor expanded into a modified cylindrical structure depending on thespecific combustion geometry. The combustion liner 300 is preferablymanufactured from a high temperature alloy, such as Haynes 230, capableof withstanding elevated combustor conditions upwards of approximately1500 deg Fahrenheit. Alternate materials can be used such as Hastelloy-Xor Inconel.

The combustion liner 300 further comprises an inlet ring basket 308secured to the generally cylindrical body 302. The inlet ring basket308, as depicted in FIG. 3-7, consists of a series of generallyaxially-oriented spindles 310 coupled to a forward ring 312 and extendsforward from the inlet end 304 of the combustion liner 300. The forwardring 312 is positioned a distance from the combustion liner 300 in orderto establish a mating location for a set of fuel nozzles (not shown) inorder to position the fuel nozzles in the proper axial position withinthe combustor. The inlet ring basket 308 can be a fabricated componentor a casting and is preferably made from a stainless steel material.Referring now to FIG. 10, the inlet ring basket 308 also includes aplurality of lugs 309 extending radially inward from the inlet ringbasket 308 for use in securing a premixer assembly 330, as discussed inmore detail below. The lugs 309 can be fabricated separately and weldedto the inlet ring basket 308 or cast as part of the inlet ring basket308.

Referring to FIGS. 4-7, the combustion liner 300 also comprises apremixer assembly 330. One component of the premixer 330 is one or moreremovable swirlers 332. Referring now to FIGS. 8-10, a swirler assembly332 is depicted in the premixer assembly 330. The swirler assembly 332comprises a premix tube 342 having an inlet end 342A and an opposingoutlet end 342B, and a longitudinal axis C-C extending therethrough. Theswirler assembly 332 also comprises a premix swirler 336 positionedwithin the premix tube 342 where the premix swirler 336 has a pluralityof turning vanes 338 for imparting a swirl to a passing flow through thepremix tube 342. For the embodiment depicted in FIGS. 8-10, the premixtube 342 is generally cylindrical. However, alternate shapes for thepremix tube 342 are possible.

The swirler assembly 332 also comprises two mounting blocks for securingthe swirler assembly in a gas turbine combustor. A first mounting block344 is positioned along an outer wall of the premix tube 342 proximatethe inlet end 342A of the premix tube 342. The first mounting block 344has a first forward face 344A, an opposing first aft face 344B, a pairof generally parallel side faces 345, and an outer face 347. The outerface 347 can have an arc-like shape to it, at least along a portion ofthe outer face, in order for the mounting block 344 to conform to theshape of the inlet ring basket 308. The outer face 347 is used to setthe radial position of the swirler assembly 332 and its contact with theinlet ring basket 308 to allow tighter dimensional control of theswirler assembly 332 relative to a fuel nozzle. The first mounting block344 also includes a plurality of first holes 348 located in thearc-shaped outer face 347 and oriented generally perpendicular to thelongitudinal axis C-C of the premix tube 342, as shown in FIG. 8.

The swirler assembly 332 also comprises a second mounting block 346positioned along the outer wall of the premix tube 342 and spaced anaxial distance from the first mounting block 344. The second mountingblock 346 has a second forward face 346A and an opposing second aft face346B, where the second aft face 346B is machined to a predetermined sizein order to form a specific axial dimension for mounting the swirlerassembly 332 in the proper axial location in the combustor. To positionthe swirler assembly 332 in the proper axial location, the secondmounting block 346 includes a relief cut 360 machined into the secondaft face 346B. The second mounting block 346 also has one or more secondholes 356 extending through the second mounting block 346 in a directiongenerally perpendicular to the plurality of first holes 348.

For the embodiment of the present invention depicted in FIGS. 8-10, thesecond mounting block 346 is in direct axial alignment with the firstmounting block 344. However, depending on the combustor geometry, thefirst and second mounting blocks 344 and 346 may not be in axialalignment, but clocked circumferentially relative to one another.

Each of the first mounting block 344 and second mounting block 346 aresecured to the premix tube 342. Different methods of attachment for themounting blocks are possible. In one embodiment, the first mountingblock 344 and second mounting block 346 are welded to the premix tube342. A bead of compatible weld material (compatible between the materialof premix tube 342 and the mounting blocks 344 and 346) is laid down atthe intersection of the mounting block and the premix tube 342.

An alternate method of securing the first and second mounting blocks 344and 346 to the premix tube 342 is through a braze joint. A braze jointwill help form a more complete joint as the entire surface of themounting block in contact with the premix tube 342 is joined to thepremix tube 342. In contrast, a weld joint only secures the mountingblock to the premix tube 342 at the edges where the mounting blockcontacts the premix tube.

In yet another embodiment, it is possible for the mounting blocks 344and 346 to be integral with the premix tube 342. The incorporation ofthe mounting blocks 344 and 346 into the premix tube 342 can beaccomplished by a casting or forging.

The exact size, spacing and quantity of holes in the first mountingblock 344 and the second mounting block 346 can vary and depends on avariety of factors such as combustor geometry, size of the swirlerassemblies 332, and mechanical and thermal loading on the swirlerassemblies 332. For an embodiment of the present invention depicted inFIGS. 8-10, the first mounting block 344 comprises two first holes 348with the first holes 348 oriented generally perpendicular to thelongitudinal axis C-C. The second mounting block 346 comprises one ormore second holes 356, and the embodiment shown in FIGS. 8-10 utilizes asingle second hole 356. However, it is possible that more than onesecond hole 356 is needed in order to secure the swirler assembly 342 toa combustor. For the embodiment shown in FIGS. 8-10, the second hole 356is generally parallel to axis C-C.

As discussed above, the swirler assembly 332 is designed to be easilyremovable from a combustor to better facilitate maintenance and repair.Therefore, a plurality of removable fasteners 350 and 358 are utilizedto secure the swirler assembly 332 in the combustor. In one embodiment,the removable fasteners, such as bolts, engage a corresponding threadpattern in the plurality of first holes 348 and one or more second holes356. A thread pattern is but one way of securing the removablefasteners. Alternatively, the one or more second holes 356 could bethrough holes (i.e. not threaded) and utilize a nut adjacent to surface346A. Furthermore, a bolt/stud could be welded/installed in lieu of hole356 with a nut then placed on the surface of the dome plate 334.

The swirler assemblies 332 are positioned so as to be in fluidcommunication with adjacent tubes 352, also referred to as hoovers,which pass the flow of fuel and air from the swirler assembly 332 to themixing zone of the combustion liner 300. That is, the swirler assemblies332 are positioned so as to be adjacent to or slightly engaged in thetubes 352. In order to ensure that the swirler assemblies 332 are in theproper radial position in the combustion liner and form a radialclearance with the tubes 352, a plurality of stand offs 354 are locatedabout the outer surface of each of the premix tubes 342, adjacent theoutlet end 342B.

As discussed above, the swirler assemblies 332 are removably secured tothe combustor through a plurality of fasteners 350 and 358, such asbolts or other means. For example, and as shown in FIGS. 6-10, the mainswirler assemblies 332 are secured to the dome plate 334 by way offasteners 350 and 358 passing through first holes 348 and second hole356. Through the use of both radially and axially oriented fasteners 350and 358, better positioning and tolerance control of the swirlerassemblies 332 relative to the premixer assembly 330 and combustionliner 300 is achieved. Furthermore, through removably securing theswirler assemblies 332 to the premixer assembly 330, access for overhauland repairs to the premixer assembly 330 is vastly improved compared toprior art combustors which had swirler assemblies welded to the premixerassembly. As one skilled in the art will appreciate, in addition toaccessibility issues, welding of the swirler assemblies also causesdeformation of the swirler assemblies, which can thereby affect flowcontrol.

The swirler assemblies 332 are preferably manufactured from a materialcomparable to the premixer assembly 330, such as a type of stainlesssteel. The swirler assemblies 332 can also be a fabricated assembly ofvarious machined parts or a casting.

Referring now to FIGS. 9 and 10, a swirler assembly 332 is showninstalled within the premixer assembly 330. As discussed above, theswirler assembly 332 is secured in position by fasteners 350 and 358,which are oriented in both a radial and axial direction. The swirlerassembly 332 is slid into position such that the standoffs 354 provide aradial clearance with respect to the tubes 352 and the second mountingblock 346 contacts the lug 309 of the inlet ring basket 308 at theproper axial location due to the relief cut 360.

The present invention has been described in relation to particularembodiments, which are intended in all respects to be illustrativerather than restrictive. Alternative embodiments and required operationswill become apparent to those of ordinary skill in the art to which thepresent invention pertains without departing from its scope.

From the foregoing, it will be seen that this invention is one welladapted to attain all the ends and objects set forth above, togetherwith other advantages which are obvious and inherent to the system andmethod. It will be understood that certain features and sub-combinationsare of utility and may be employed without reference to other featuresand sub-combinations. This is contemplated by and within the scope ofthe claims.

1. A swirler assembly for a gas turbine combustor comprising: a premixtube having an inlet end, an opposing outlet end and a longitudinal axisextending therethrough; a premix swirler positioned within the premixtube, the swirler having a plurality of turning vanes for imparting aswirl to a passing flow; a first mounting block positioned along anouter wall of the premix tube proximate the inlet end and having aplurality of first holes oriented generally perpendicular to thelongitudinal axis; and, a second mounting block positioned along theouter wall of the premix tube a distance from the first mounting block,the second mounting block has one or more second holes extending throughthe second mounting block in a direction perpendicular to the pluralityof first holes.
 2. The swirler assembly of claim 1, wherein the premixtube is generally conical.
 3. The swirler assembly of claim 1, whereineach of the first mounting block and second mounting block are securedto the premix tube.
 4. The swirler assembly of claim 3, wherein thefirst and second mounting blocks are secured to the premix tube by aweld or braze joint.
 5. The swirler assembly of claim 1, wherein theplurality of holes in the first mounting block comprise at least twoholes.
 6. The swirler assembly of claim 1, wherein the one or moresecond holes is threaded.
 7. The swirler assembly of claim 1, whereinthe second mounting block has a second forward face and opposing secondaft face, where the second aft face is finish machined to apredetermined axial dimension.
 8. A multi-point, multi-directionalfastening assembly for use in a gas turbine combustor comprising: afirst mounting block secured to a body, the first mounting block havinga first forward face, an opposing first aft face, a pair of side faces,an outer face, and a plurality of holes located in the outer face; and,a second mounting block secured to the body, the second mounting blockhaving one or more holes located therein; wherein the second mountingblock is spaced an axial distance from the first mounting block.
 9. Thefastening assembly of claim 8, wherein the outer face is arc-shaped atleast at regions surrounding the plurality of holes.
 10. The fasteningassembly of claim 8, wherein the first mounting block is secured to thebody by a weld or braze joint.
 11. The fastening assembly of claim 8,wherein the second mounting block is secured to the body by a weld orbraze joint.
 12. The fastening assembly of claim 8, wherein the firstand second mounting blocks are integral to the body.
 13. The fasteningassembly of claim 8, wherein the plurality of holes in the firstmounting block are generally perpendicular to the one or more mountingholes in the second mounting block.
 14. A removable swirler assembly ina combustor comprising: a generally cylindrical body; a center corepositioned within the cylindrical body proximate an inlet of thegenerally cylindrical body; a plurality of vanes extending between thecenter core and the generally cylindrical body; a first mounting blocksecured to the generally cylindrical body, the first mounting blockhaving a first forward face, an opposing aft face, a pair of side faces,and an outer face having a plurality of holes located therein; and, asecond mounting block secured to the generally cylindrical body, thesecond mounting block having one or more holes located therein; whereinthe removable swirler is fastened to the combustor at both the firstmounting block and second mounting block through a plurality ofremovable fasteners.
 15. The removable swirler of claim 14, wherein theplurality of vanes are oriented so as to impart swirl to a passing flowof air and fuel.
 16. The removable swirler of claim 14, wherein thefirst mounting block extends in a circumferential distance greater thanthe second mounting block.
 17. The removable swirler of claim 14,wherein the plurality of holes in the first mounting block are generallyperpendicular to the single hole in the second mounting block.
 18. Theremovable swirler of claim 14 further comprising a plurality offasteners placed into the plurality of openings of the first mountingblock for securing the swirler to the combustor.
 19. The removableswirler of claim 14, wherein the outer face of the first mounting blockis arc-shaped at least at regions proximate the plurality of holes.